Large flexible fabric bags for containing and transporting flowable granular or powdered bulk material such as chemicals, minerals, foodstuff, agricultural products, pharmaceutical and cosmetic ingredients and the like have been used for many years and their use is becoming increasingly more popular. This is due to their relatively low cost and the fact that when the bags are empty, they take up very little space and are relatively light in weight. When filled, the flexible bulk containers may carry a cubic meter or more of material and may weigh in excess of two tons.
The bags used for such purposes have to fulfill several practical requirements. It is of primary importance that the construction of the bag must be such as to sustain heavy loads but, at the same time, the bag must be adapted to be folded or collapsed when empty to a compact and preferably flat form. Frequently, because of the nature and quantity of material shipped in such bags, the bags should also be designed so that they can be easily filled with large quantities of granular and powdered bulk materials and then readily emptied of their contents. It is also desired that such bags be designed so that, when filled, they can be easily handled, and are generally free standing and capable of being stacked vertically one upon another. Furthermore, depending upon the type of material being shipped, some fabric bulk bags may be required to be moisture proof, water resistant and/or hygienic, or requirements may be such that the contents such as food products must be sealed for the purpose of purity, in which case a polyethylene or the like liner is provided.
A variety of bags and bag constructions have been suggested and used as flexible bulk containers such as disclosed, for example, in U.S. Pat. Nos. 3,961,655; 4,113,146; 4,730,942; 4,781,472; 4,822,179; 4,909,410 and European patent publication No. 338,181. Although these bags and containers are common in industry, there are several shortcomings which have been encountered and warrant further attention. For example, while the design, flexibility and light weight of many such bags renders them readily collapsible for convenient return by the user to the shipper for reuse, during the handling and storage of the bags they frequently come in contact with contaminants such as dirt, grease and the like which are deposited on or within the bags. Such contaminants are not only unsightly, but in many cases, the product within the bag is a food product or pharmaceutical ingredient where protection from contamination is essential. Fabric bulk containers in common use cannot be readily cleaned and in such instances, even the use of plastic liners and the like may not provide sufficient hygienic purity, and disposal of the fabric bag is generally necessary. However, if the bag could be readily and thoroughly cleaned prior to reuse, such contamination problems could be essentially eliminated and would be a highly desirable objective in making possible reuse of the bag as well as for protecting the purity of products to be shipped and stored.
In addition, when a polyethylene or the like liner is used in connection with such large fabric bulk bags to contain particulate or granular material whereby the liner is insertable into the exterior fabric bag and the bag is formed with an opening or a spout at one end for discharging the contents, a common problem is the tendency for the particulate contents, when discharged, to draw the liner out of the bag. If the liner is not secured within the bag, the result is often that the liner itself will drop from the bag into the receiving container or bin and this could contaminate the contents which would be undesirable. It is, thus, common practice to secure the liner within the bag, using techniques such as disclosed, for example, in U.S. Pat. Nos. 4,781,472 and 4,946,241. However, due to the size of both the bags and liners, such known means for securing the liner within the bag are generally inconvenient and difficult to use.
Moreover, during the filling of such bags with a product, a great deal of dust can be generated which settles on exposed portions of the bag and liner, and as indicated, during the handling and storage of the bags, they frequently come in contact with contaminants such as dirt, grease, oil and the like against which the contents must be protected. In U.S. Pat. No. 4,909,410 there is suggested a bulk container with a removable protective cover for the outer surfaces of the container in the form of a skirt which is integrally secured to seams of the container. Such protective cover is removed from the bulk container to eliminate contaminants that may have been deposited on the external surface thereof but once removed, the container would have to be reconstructed for replacement of the protective cover and there is no other suggestion therein for cleaning the container itself for possible reuse. Other devices such as removable covers have also been suggested for use with small hand-carried shopping bags and the like to protect the contents thereof against dirt and the elements have also been suggested, for example, in U.S. Pat. Nos. 3,349,992 and 4,930,903. The shopping bags and the like containers employing such protective covers are substantially different in construction and use than the large bulk containers used for shipping and storage of bulk materials and the problems associated therewith are significantly different. Providing large, flexible bulk containers with a device which protects both the container surfaces and the contents thereof from being contaminated during filling, handling and storage would be particularly advantageous.